Presently, there are mainly two technologies available for removing particles in air as follows:
I. A filter formed by folding non-woven fiber filter papers, represented by HEPA (High Efficiency Particulate Air Filter), which intercepts particles through sieving, bridging, impact adhesion, absorption by electric field created by electrostatic electret fiber and others. With such advantages as simple structure and high efficiency, it is widely applied. However, HEPA suffers from the following disadvantages:
1) Greater air resistance. The preset air quantity requires a blower of greater power, and this causes large energy consumption and loud noise.
2) It requires regular replacement, and is not reusable, leading to huger costs.
II. An electrostatic dust collection device, represented by ESP (Electrostatic Precipitator) using the corona-collection mode. With such advantages as low air resistance and good reusability, it is also widely applied. However, ESP has also its disadvantages that cannot be easily overcome as below:
(1) Corona discharge may produce ozone. Though ozone produced can be controlled by an ozone catalytic filter, it is likely to go beyond the increasingly stricter concentration control index range, and do harm to bodily health.
(2) The slight inter-electrode lighting discharge noise is what the users usually complain of, and it also impairs the product's use safety.
(3) As the breakthrough voltage is limited by the open structure, EPS has lower single filtering efficiency.
(4) The complex high-voltage power supply and high-voltage safety precautions are required, and so the device costs are improved.
(5) EPS structure, especially circuit board structure, is quite fragile and liable to damages when cleaned.
To remove such disadvantages of EPS as above, the public specification of the invention patent application, China Patent Application No. 00806175.0, discloses an “air purification device” that is developed from EPS. The technical solution adopted by the invention can be described as follows: a device used to remove particle deposit from air, including hole arrays through which air can relatively freely pass, and said hole arrays disposed between plastic walls; a device used to force air to pass through hole arrays, and said plastic walls having a conductive material zone that comes in contact with said device; and a device used to apply high and low potentials to the insulated conductive material zone alternately, to create an electric field in arrays, so that it can capture particles from air.
Said solution presents a series of structures and modes of combination, and “disposing electrodes on both surfaces of the plastic double walled waveform boards, and then stacking said boards alternately” is an important embodiment of the invention, but there are still many problems not solved yet, including:
1. The symmetric dust collection board structure with smooth inner walls, due to Faraday cage effect, is unable to efficiently capture uncharged (neutral) particles, and so needs a negative ion generator or to reduce the height of the dust collection boards or longer holes, which may bring about many adverse effects, including greater air resistance, over large size of installation and others.
2. The electrodes come in direct contact with the outside of the plastic injected dust collection boards, as a result of which said electrodes may, in the presence of micropore plastic injection defects in the dust collection boards, discharge to air or relevant inner wall, and produce odor.
3. To meet the requirements for waterproofing and entire structure strength, adhesives are applied between the dust collection boards, especially two component adhesives that can enhance adhesion of PP materials. The use of said adhesives may cause odor to long exist in the filter, and result in secondary air pollution.
4. The electret mentioned in said solution cannot generate charges that can be long stored for the plastic materials mentioned therein, and said charges stored on surfaces may be gone several days or weeks later.
5. The repetitively stacked structure may still produce greater plate condenser effect. Although the high-impedance electrodes are used, or the drain resistors are disposed at the electrode end, it is still likely that an electric shock takes place in the exposed contact zone within the early several seconds.
6. The external high-voltage input mode used is the same as ESP's power supply mode, and so a complex safety circuit is needed.
7. The non-enclosed structure may allow the electrodes to come in contact with air and water, and so said electrodes are easily liable to aging and leakage, which may cause harm to the repeated water washing process.
To solve the problems above, the inventors, through lots of studies and experiments, now present the solutions as follows:
Contents of Invention:
The technical problems to be solved by the present invention are the defects in the existing similar products, and it is designed to provide an integrated electrostatic dust collection device that can improve capturing efficiency and features safe use and simple operation.
To solve the technical problems above, the present invention adopts the technical solution as follows: the device includes the outer frame and the main body packaged in said outer frame, said main body consists of several integrated micro electrostatic dust collection cells that are distributed in the form of array, the each said micro electrostatic dust collection cell has a linear or curvilinear hole for air to pass through, the upper and lower walls of said hole are non-symmetric, on which the eudipleural fins are disposed, and the upper and lower surfaces of the each said micro electrostatic dust collection cell are disposed with an enclosed conductive film applied with a high-voltage electric field; the high-voltage power supply used to create a high-voltage electric field is packaged in said outer frame, and a contact or socket on said outer frame is used externally to supply low-voltage power.
Furthermore, said micro electrostatic dust collection cells are integrated on a dust collection board. Said dust collection board is formed by injecting materials of electret nature, to which any kind of the following materials or combination thereof can be added: a) microporous foaming agent using nitrogen as micro-foaming gas, whose mass ratio ranges between 0.1% and 10%, and which can form lens like or spindle shaped micro-bubbles; b) first additive that can enhance the electret performance and extend the storage time of charges, including disproportionated rosin, PVDF, PTFE, calcium stearate, aluminum palmitate and ferroelectrics, which can be added alone or in a combined fashion, adding mass ratio ranging between 0% and 20%; c) second additive possessed of natural electret characteristics and emission characteristic of negative ion, including mixture of electrical powder or tourmaline and lanthanide series, adding mass ratio ranging between 0% and 15%; d) third additive made of magnetic powders, including dyestuff mainly containing Fe3O4, ferrite material and Nd—Fe—B material that can be externally magnetized, adding mass ratio ranging between 0.1% and 5%.
Furthermore, in said technical solution, said enclosed conductive film forms the “film-electrode-film” composite structure through adhesion, thermal sealing and ultrasonic, and the electrode is made on a layer of film in the intended pattern through printing or vacuum coating.
Furthermore, in said technical solution, said film refers to thin film, hole film and microporous film, and they are made of PP, PE, PET or PTFE. Said electrode is formed by: a) low-resistance self-healing vacuum aluminum film, resistance ranging between 0.1 Ω/m and 100 Ω/m; or b) high-resistance printable film that is made of metal oxide, carbon macromolecular conductive material and adhesive material, resistance ranging between 10E8 Ω/m and 10E11 Ω/m. And said high-resistance electrode is printed in the intended pattern, and said pattern is a herringbone pattern having line edges and sharp prickles on it, and the coverage of electrode varies from 10% to 90%.
Furthermore, in said technical solution, the dust collection boards contained in said main body are stacked in such a order as: dust collection board-low-potential film electrode-dust collection board-high-potential film electrode-dust collection board, the safety distance of 0.5˜1.5 mm/Kv is reserved between the edge of the film electrode and the edge of the dust collection board, and the electret polarity of the dust collection board corresponds to the electrode potential. The two adjacent dust collection boards are alternately stacked at an angle of 1˜30°.
Furthermore, in said technical solution, said main body is disposed with one or more negative ion dust collection board (s) having built-in negative ion emission electrode, within the hole of said negative ion dust collection board a negative ion emission electrode is housed, and said hole of the negative ion dust collection board is of symmetric structure. Near the end a needle or prickle-like brush emission electrode made of W, Mo or stainless steel or a filamentous brush emission electrode made of conductive carbon fiber is disposed, and the distance from the emission electrode to the end is 1.0˜1.5 mm/KV.
Furthermore, in said technical solution, said two adjacent dust collection boards are joined through hot-melt adhesive or binder, and the edges of these two adjacent dust collection boards are bonded through thermal fusion into an enclosed edge.
Furthermore, in said technical solution, said high-voltage power supply is installed at any side of the main body where neither inlet nor outlet is set. The output end of said high-voltage power supply is connected to ends of high and low potential of each electrode film through collective line, and the negative high-voltage end of said high-voltage power supply is connected to the negative ion emission electrode on the negative ion dust collection board.
Furthermore, in said technical solution, said outer frame is made of plastic or metal, and the main body and the high-voltage power supply are integrally packaged in the outer frame through sealing process, namely, a seal coating is formed between the outer frame and main body, and on the outer frame a socket or contact is installed for supplying power to the high-voltage power supply.
To further improve the integration effect of the integrated-structure electrostatic dust collection device mentioned in said technical solution, the present invention adopts the following electret processing technique, and said electret processing consists of three steps as follows:
I. The dust collection boards are once shaped by the injection molding machine, and during this process, the dust collection boards also undergo electret processing and magnetization. The process consists of four steps as follows: a) the first positive or negative corona electret processing is conducted at the outlet of the injection mold and the inlet of the cooling section, using such tools as needle board, wire board, wire, needle-medium baffle and wire-medium baffle, and the voltage difference of the electret varies from 10 Kv to 50 Kv; b) the second electret processing is conducted between the cooling section and traction section using needle board, wire board and wire-wire type electret, in which the polarity is opposite to that in the a) step, and the voltage difference of the electret varies from 5 Kv to 30 Kv; c) At the front end of the cutting device, the third electret processing is conducted with the same electret and polarity as the a) step, and the voltage difference of the electret varies from 20 Kv to 70 Kv; d) A magnetization mechanism is set between the corona device having experienced the third electret processing above and the cutting device, the magnetic field strength being 0.1˜10 T.
II. Electret processing of the enclosed conductive film. The film electrode in the enclosed conductive film is connected to the high-voltage power supply, and the electric field formed by the heating zone and cooling zone is applied to perform continuous electret processing.
III. After the filter finishes its integral packaging, the electret device is used to conduct entire electret processing, which consists of the steps as follows: first, the contact or socket is allowed to supply power to the filter, and in the state of power supply, the subsequent steps are performed;
Next, the vapor or hot air is used to heat the filter to 70˜100° C., and the reached temperature is maintained for 0˜30 min; then, the filter is placed in the heater for 0˜60 min at 60˜80° C.; last, air or cool air is allowed to quickly pass through the holes of the dust collection boards of the filter for 1˜20 min, to cool down the filter.
The present invention adopts the above-mentioned technical solution to form an integrated-structure electrostatic dust collection device (Uni-ESP). Compared with the current similar products, the invention has the following advantages:
1. The upper and lower walls of the rectangular holes on the dust collection boards are of non-symmetric design, on which the fins are distributed. The use of the non-symmetric structure increases the internal surface area of the holes, shortens the distance between the internal surface walls, allows the particles to come into contact with the inner walls and then be captured within a shorter range, and realizes greater capturing efficiency by use of possibly shortest holes.
2. The use of the non-symmetric structure renders distribution of the internal electric field non-symmetric, so that the non-charged particles or those that cannot be easily charged can be efficiently captured.
3. In the present invention, the hole arrays of curved structure can also be made. When air carrying particles passes through the hole arrays, the particles can more easily come into contact with the hole walls and so be more efficiently captured.
4. To the plastic materials making up the hole walls and fins the additives that can enhance electret performance and extend the storage time of charges can be added, to charge the particles passing through the invention and so improve the dust collection effect.
5. The present invention can be installed with a negative ion emission device in it, so that in the presence of air flow, the negative ions generated can be diffused to air, to charge the particles and so improve the dust collection effect.
6. In the present invention, to the plastic materials making up the dust collection boards the magnetic materials can also be added, which may create a magnetic field on the upper and lower surfaces of the dust collection boards through external magnetization. Under the action of the magnetic field, the charged particles deflect to right and left from their course due to Lorentz force, and are then captured onto the surfaces of the right and left inner walls of the holes. In this way, the present invention uses both electric field deflection and magnetic field deflection techniques, increasing particle capturing efficiency, making full use of all surfaces of hole walls, and also improve dust containing capacity.
In addition, to further enhance the dust collection effect, the present invention presents solutions to the problems that the general plastic materials have poorer electret performance and that the storage time of the electret charges is shorter, and it also discloses an electret processing technique. The electret processing technique means that the materials used for the dust collection boards are directly charged by electret during their injection molding, and the filter is charged as a whole, to further enhance the electret performance. Said electret processing technique combines electret charging and magnetization techniques for the dust collection boards, so as to maximize charge capturing efficiency, obtain high-voltage and long-duration electret material, and also create a magnetic field of even distribution. And the present invention also discloses an entire electret processing method for the integrated-structure electrostatic dust collection device, to endow the device with better performance.
To realize a stronger electric field and safer use, the present invention designs an enclosed conductive film of 3-layer structure. The film structure designed by the present invention provides adequate insulation and protection for the conductive film, frees the conductive film from the insulation problem arising during its use or caused by entry of water during its cleaning, and also protects the conductive film from change in resistance value and break due to ageing during its service.
The present invention designs an integrated structure. The electrodes of high and low potentials, after gathered, are connected to the high-voltage power supply installed at any side other than inlet or outlet side, and then the plastic or metallic outer frame are used to form an integrated-structure electrostatic dust collection device through sealing and packaging. On the outer frame a contact or socket for supplying power to the transformer is installed, and in this way, an integrated-structure electrostatic dust collection device (Uni-ESP) is formed.